Note: Descriptions are shown in the official language in which they were submitted.
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* * * SPECIFICATION * * *
; This invention relates to a process for the con-
version of mercaptan-containing compounds in a petroleum
distillate charge stock. More specifically, this invention
relates to the conversion of a petroleum distillate charge
stock cont.aining mercaptan, olefinic and dienic compounds
comprising the treatment of said petroleum distillate in an
atmosphere of an oxygen-containing gas in a medium posses-
sing of from about a pH of 8 to about a pH of 14 in the pres-
ence of a catalyst comprising a 4,4',4",4"'-cobalt phthalo-
cyanine tetrasulfonate.
The art of mercaptan conversion in petroleum distil-
lates is well known in prior treatment art. For example, it
is well known that a gasoline charge stock containing various
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mercaptan compounds may be treated using metal phthalocya-
nine compounds for the conversion of the mercaptan compounds
contained in the gasoline charge stock to disulfide compounds.
menecessity of the conversion of the mercaptan compounds in
S a petroleum distillate charge stock is as a result of the bad
odor of the mercaptan compounds which necessitate conversion
to a "doctor-sweet" product. The easiest means of conversion
known to the art is by means of the oxidation of the mercaptan
compounds to disulfide compounds. The difficulty of con-
verting the mercaptan compounds will depend on which mer-
captan compounds are present in the petroleum distillate charge
stock. In lighter charge stocks such as a straight run gaso-
line the mercaptans comprise lower alkyl mercaptans which are
fairly easily oxidized by any of the metal phthalocyanine cat-
alysts known to the art. However, as the complexity of theblend of the charge stock increases the complexity of the dif-
ferent mercaptan compounds will increase and therefore the de-
gree of difficulty of conversion also becomes greater. Petro-
leum distillate charge stocks which are high in mercaptan, ole-
finic and dienic compound content such as an FCC gasoline chargestock will contain very difficult to convert mercaptans such as
aromatic mercaptans or branched chained alkyl mercaptans such
as dodecyl mercaptan. It is known as a problem of mercaptan
treating or conversion that certain FCC gasoline charge stocks
possess unconvertible mercaptan compounds in the presence of
certain catalytic compositions of matter. For example, it is
known that a mercaptan-containing FCC gasoline charge stock is
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very difficult to convert to a sweet or substantially mer-
captan-free FCC charge stock in the presence of 4,4'-cobalt
phthalocyanine disufonate.
In contradistinction to the prior art it has now
been discovered that mercaptans found in an FCC gasoline
charge stock may be converted to disulfides by treatment
in an atmosphere of an oxygen-containing gas in a medium
possessing a pH of from about a pH of 8 to about a pH of 14
in the presence of a catalyst comprising 4,4',4",4"'-cobalt
phthaiocyanine tetrasulfonate. The utilization of the above
set forth invention will allow the operator of fluid cataly-
tic cracking units to obtain a doctor sweet reactor effluent
as a result of conversion of the until now very difficult to
convert mercaptan materials present in the FCC gasoline charge
stock effluent. The utilization of this invention will also
allow the manufacturer or refiner a more ecologically feasible
method for the preparation of petroleum distillates which are
high in dienic and olefinic compound content as a result of
the elimination of harmful and bad odorous compounds.
The utilization of the present invention is set forth
in the ability of the process of the present invention to take
a foul or sour petroleum distillate such as an FCC gasoline
charge stock and treat said stream to a doctor sweet effluent
for the betterment of the refiner and the ecology.
It is therefore an object of this invention to provide
! a process for the conversion of mercaptan compounds in a petro-
leum distillate charge stock containing high mercaptan, dienic
and olefinic compound content.
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Further, it is an object of this invention to
provide a process for the conversion of mercaptan compounds
in an FCC gasoline charge stock utilizing a composition of
matter which will better effect the mercaptan conversion to
disulfides.
In one aspect an embodiment of this invention re-
sides in a process for the conversion of a petroleum distil-
late charge stock containing mercaptan, olefinic and dienic
compounds comprising the treatment of said petroleum distil-
late in an atmosphere of an oxygen-containing gas in a medium
possessing a pH of from about a pH of 8 to about a pH of 14
in the presence of a catalyst comprising a 4,4',4",4"'-cobalt
phthalocyanine tetrasulfonate at treatment conditions and re-
covering the resultant treated charge stock.
A specific embodiment of this invention resides in
~ a process for the treatment of an FCC gasoline charge stock
- containing 240 parts per million mercaptan in said charge
; stock in the presence of air, a sodium hydroxide medium pos-
sessing a pH of about 11 and a catalyst dissolved in said
medium comprising 4,4',4",4"'-cobalt phthalocyanine tetrasul-
fonate at a temperature of 25C. and a pressure of 1 atmosphere
and recovering the resultant treated FCC gasoline charge stock
after a period of time comprising 4 minutes.
Other objects and embodiments of the hereinbefore set
forth invention will be discussed in the following further
detailed description F the presen~ invontion.
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As hereinbefore set forth the present invention
is concerned with the treatment of a petroleum distillate
charge stock containing mercaptan, olefinic and dienic com-
pounds comprising the treatment of said charge stock in an
atmosphere of an oxygen-containing gas in a medium posses-
sing a pH of from about 8 to about a pH of about 14 in the
presence of a catalyst comprising a 4,4',4",4"~cobalt
phthalocyanine tetrasulfonate at treatment conditions. The
treatment conditions will include a temperature of from a-
bout 15C. to about 300C. and a pressure of about 1 atmos-
phere to about 100 atmospheres. When atmospheric pressures
afforded in the process of this invention are superatmos-
pheric pressures they may be afforded by the introduction
of the oxygen-containing gas to the treatment zone or, if
desired, any substantially inert gas may be intermixed with
the oxygen-containing gas to afford the total pressure of
the system whereby the partial pressure of the system is
equal in sum to the total pressure~of the treatment system.
Suitable oxygen-containing gases will include oxygen,
oxygen-nitrogen mixtures (air), oxygen-xenon mixtures,
oxygen-nitrogen-helium mixtures, oxygen-helium mixtures,
oxygen-argon-krypton, etc.
The charge stock of this invention is defined as a
petroleum distillate containing mercaptan, olefinic and dienic
compounds. The quantity of the mercaptan compounds will range
from 20 ppm mercaptan as sulfur to about 1000 ppm mercaptan as
sulfur. The diene content of the petroleum distillate of the -.
present invention will range from 0.5 grams of dienic compounds
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to about 3.5 grams of dienic compounds as determined by
the grams of iodine per 100 grams of petroleum distillate.
The olefinic compounds will range from about 20.0 grams
to about 70.0 grams of olefinic material as determined by
S the grams of bromine per 100 grams of petroleum distillate,
A suitable example of the petroleum distillate will com-
prise an FCC gasoline petroleum distillate. It is known
in the art of catalytic cracking of gasoline that FCC gaso-
line petroleum distillates possess different chemical pro-
perties depending on such factors as the original chargestock ingressed to the FCC unit, the catalytic composition
of matter within the FCC unit and the method of performing
the catalytic cracking of the original charge stock. It is
contemplated within the scope of this invention that any
gasoline derived from an FCC unit may be utilized as the
petroleum distillate charge stock. The mercaptan content
of FCC gasoline petroleum distillates is usually one that
is aromatic in nature such as thiophenol. The mercaptan con-
tent may also be aliphatic in nature such as methyl mercaptan,
ethyl mercaptan, propyl mercaptan, butyl mercaptan, amyl mer-
captan, hexyl mercaptan, heptyl mercaptan, nonyl mercaptan,
decyl mercaptan, or other various straight chained aliphatic
mercaptan compounds containing from about 1 to about 20 carbon
atoms. The mercaptan-content of the FCC gasoline petroleum
distillate may also comprise branched-chain aliphatic mercap-
tan compound such as dodecyl mercaptan or other various hard
to treat mercaptan compounds. The thiophenoIic mercaptan com-
pounds may be substituted with other substituents such as
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alkyl, carboxyl, alkoxy, aryl, alkaryl, aralkyl or alco-
holic moieties.
The catalytic composition of matter of the present
invention will comprise a 4,4',4",4"'-cobalt phthalocyanine
tetrasulfonate compound. This compound is known in the art
to be made by various methods of catalyst manufacture. One
such method of catalyst manufacture is the reaction of tri-
ammonium sulfophthalate with urea and cobalt sulfate hepta-
hydrate in the presence of boric acid. It is contemplated
within the scope of this invention that the catalytic compo-
sition of matter may be present in the form of a liquid-li-
quid two phase petroleum distillate charge stock-4,4',4",4"'-
cobalt phthalocyanine tetrasulfonate system. The liquid-li-
quid system is defined as having two phases one of which is
the petroleum distillate charge stock containing mercaptan,
olefinic and dienic compounds and the second of which is
the cobalt phthalocyanine tetrasulfonated catalyst which may
be present in a reaction medium which is liquid in nature and
possesses a pH of from about a pH of 8 to about a pH of 14.
The conversion of the mercaptan compounds in the liquid-li-
.~ quid system will be effected at the interface of the two sys-
; tems on the basis of contact with the catalytic compositions
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of matter. The reaction medium of the liquid-liquid system
will comprise any alkaline material such as sodium hydroxide,
potassium hydroxide, lithium hydroxide, rubidium hydroxide,
cesium hydroxide, barium hydroxide, strontium hydroxide, cai-
cium hydroxide, magnesium hydroxide, beryllium hydroxide, am-
monia hydroxide, pyridinF, piperldine, picoline, lutidin~, ;
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quinoline, pyrrole, indole, carbazole, acridine or anysuitable quaternary ammonia compounds such as tetrabutyl
ammonium hydroxide, tetraamyl ammonium hydroxide, tetra-
propyl ammonium methoxide, tetraamyl ammonium methoxide,
tetraethyl ammonium ethoxide, diethyl amine, triethyl
amine, tetramethylenediamine, tetraethylenepentamine,
phenylenediamine, however, the pH in the reaction medium
will range from about a pH of 8 to a pH of about 14 or
more preferably a pH of from about 9 to about a pH of 11.
In a preferred embodiment of the present inven-
tion the catalyst system of the present invention will al-
so comprise a catalyst system which may be present as a
fixed bed system. The fixed bed system of catalytic treat-
ment is well known in the art and it is contemplated within
the present invention that the 4,4',4",4"'-cobalt phthalo-
cyanine tetrasulfonate is dispersed on the fixed bed. The
fixed bed will comprise any solid material such as alumina,
silica, magnesia, thallia, zirconia, carbon, charcoal, y -
alumina, mordenite, faujasite, pumice, etc.
The 4,4',4",4"'-cobalt phthalocyanine tetrasulfonate
may be present in the total catalyst system in a weight per-
cent relative to the entire reaation system of from about
.0001 weight percent to about 10.00 weight percent. ~he afore-
mentioned weight peraentages are applicable to both the fixed
- 25 treatlng system and the liquid-liquid two phase petroleum dis-
tillate aharge stoak-4,4',4",4"'-aobalt phthaloayanine tetra-
sulfonate system.
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The resultant treated charge stock will comprise
a petroleum distillate charge stock containing substantially
the same quantity of olefinic and dienic material but a
greatly reduced mercaptan content. The mercaptan compounds
are converted to disulfide compounds to the extent that the
resultant petroleum distillate is substantially free of mer-
captan compounds. The remaining quantity of mercaptan com-
pounds will be small enough to qualify the petroleum distil-
late as a doctor sweet petroleum distillate. The term doc-
tor sweet is relative to the type of analysis to determinemercaptan content but will range from about 5 ppm mercaptan
as sulfur in gasoline to about 20 ppm mercaptan as sulfur in
kerosene petroleum distillates.
It is understood that the aforementioned mercaptan,
catalytic systems and fixed beds are only representative of
the class of compounds which may be employed in the present
invention and the present invention is not limited thereto.
The following examples are introduced to illustrate
the further novelty and utility of the present invention but
not with the intention of unduly limiting the same.
EXAMPLE I
This example was effected for the purpose of com-
paring the treatment of an FCC gasoline charge stock utilizing
a disulfonated cobalt phthalocyanine compound in contrast to
the treatment of a catalyst comprlsing a cobalt phthalocyanine
tetrasulfonated compound of Example II. The unexpected re-
sults of the present invention may be viewed from the increased
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1081~52
conversion of the mercaptan compounds of Example II in
the presence of the tetrasulfonated compound over a shor-
ter period of time in contradistinction to the limited
conversion of the mercaptan compounds in the presence of
the disulfonated compound of Example I. The disulfonated
cobalt phthalocyanine compound was prepared and analy~ed
and found to contain a spectrum of the sulfonated deriva-
tives as set forth in Table I below
TABLE I
ISOMER . WEIG~T PERCENT
Monosulfonate 6.3
Disulfonate 59.6
Trisulfonate 25 6
Tetrasulfonate 8 5
100.'0
This aforementioned catalyst was used to treat an FCC gaso-
line charge stock in a reaction medium comprising 10 Be'
- caustic of sodium hydroxide over a period o time comprising
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8 minutes in the presence at a temperature of 25C. and a
pressure of 1 atmosphere. The relative mercaptan content
over the 8 minute period of time is set forth in Table II
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TABLE II
TIME WT.~-PPM MERCAPTAN
o 240
2 25
4 23
6 15
- .Doctor Sweet
8 ~ 4 .
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EXAMPLE II
In this example a tetrasulfonated catalyst was pre-
pared and analyzed and found to contain 100% tetrasulfonate
isomer of cobalt phthalocyanine tetrasulfonate. This cat-
alyst was used in the treatment of a similar aliquot por-
tion of the FCC gasoline charge stock utilized in Example
I in the presence of the same reaction medium comprising
sodium hydroxide and in the presence of the same quantity
of air and reaction temperature and pressure. The results
10 of the mercaptan sweetening process are set forth in Table
III below
TABLE III
TIME WT.-PPM MERCAPTAN
o 240
2 13
4 2 Doctor sweet
6 Cl
8 ~1
A comparison of Example II with Example I in the treatment
of the same aharge stock will show the unexpected results
of the present invention. In Example I the mercaptan con-
tent after the 4 minute period of time was 23 parts per mil-
lion in comparison with the 2 parts per million mercaptan con-
tent of the tetrasulfonated catalyst treatment process of Ex-
ample II. It can also be seen that it required between 6 to8 minutes in Example I to render a doctor sweet product where
in the Example II utilizing the tetrasulfonated cobalt phthalo-
cyanine derivative the doctor sweet product was formed some-
where between 2 and 4 minutes.
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EXAMPLE III
In this example a FCC gasoline charge stock con-
taining mercaptans,olefins and dienes is treated in a medi-
um comprising sodium hydroxide and air in a fixed bed
method of treatment which comprises the passage at a LHSV of
3.0 of the FCC gasoline mercaptan-containing charge stock
- over a fixed bed of 4,4',4",4"'-cobalt phthalocyanine tetra-
sulfonate dispersed on y-alumina. The treatment is effect-
ed at a treatment temperature of 100C. and a pressure of 5
atmospheres as afforded by the introduction of the air to
the reaction system. The FCC gasoline charge stock is re-
covered subsequent to the fixed bed and analyzed for mercap-
tan content, said mercaptan content analysis showing a doc-
tor sweet FCC gasoline.
